Mycobacterium tuberculosis Complex Infection in a Dog Jane E. Sykes, Allison B. Cannon, Aimee J. Norris, Barbara A. Byrne, Timothy Affolter, Michael A. O’Malley, and Erik R. Wisner A 9-year-old spayed female Golden Retriever, weighing 40.1 kg, from Fairfield, California, was evaluated at the University of California, Davis, Veterinary Medical Teaching Hospital in August of 2004 for evaluation of a 2-month history of a cough, lethargy, and progressive inappetence. The cough was occasionally productive and occurred multiple times a day. Results of routine CBC and blood chemistry tests performed by the referring veterinarian were unremark- able, and thoracic radiographs revealed right cranial lung lobe consolidation and hilar lymphadenopathy. The dog was treated with amoxicillin (25 mg/kg PO q8h), without improvement. The dog also had a history of urinary tract infections that had been treated intermittently with enrofloxacin. One year before pre- sentation, the dog had been acquired from a rescue organization, which, in turn, had acquired the dog from a pet store in northern California. Other pets in the current household were 29 parakeets. On examination, the dog was alert, hyperthermic (103.2uF [39.6uC]), panting, and had a body condition score of 8 of 9. Abnormalities of cardiac rate or rhythm were not detected. Thoracic auscultation revealed harsh lung sounds bilaterally. Thoracic radiographs revealed right cranial lung lobe consolidation, with interstitial to alveolar infiltrates in the right middle lung lobe. A lobular soft-tissue opacity was noted dorsal to the carina on the right lateral projection that was thought to represent hilar lymphadenopathy or a juxtahilar mass. An abdominal ultrasound examination disclosed no abnormalities. Serology for Coccidioides antibodies was negative. Cytologic analysis of fine needle aspirates from the consolidated lung tissue revealed mild inflammation that consisted of activated macrophages, nondegenerate neutrophils, and small mature lymphocytes. Several small clusters of cuboidal epithelial cells were observed, with high nuclear : cytoplasmic ratios and variably distinct borders, some of which were suggestive of an adenocarcinoma. A small amount of pink, fibrillar material was noted, consistent with collagen. There was also a small amount of mucinous material, mineralized debris, and cholesterol crystals suggestive of necrosis. The owner declined further diagnostic testing. Treatment with clavulanic-acid amoxicillin a (25 mg/ kg PO q12h), enrofloxacin b (3.4 mg/kg PO q12h), and piroxicam c (0.25 mg/kg PO q24h) for 4 weeks resulted in improvement in the dog’s appetite and cough, but, on discontinuation of this therapy, the inappetence, cough, and lethargy returned. Physical examination 7 weeks after initial presentation disclosed mild weight loss (body weight, 36.2 kg). Thoracic radiographs showed extension of the right cranial lung lobe consolidation and persistent hilar lymphadenopathy. The previous treatment was reinstituted, and the dog’s condition again improved. Eight months after initial examination, thoracic radiographs were unchanged. Urine culture for aerobic bacteria revealed Escherichia coli that was resistant to enrofloxacin and clavulanic acid–amoxicillin. Antimi- crobial therapy was changed to chloramphenicol d (38 mg/kg PO q8h), which was discontinued after 2 weeks because the dog was vomiting. Because the coughing worsened, the owners elected to pursue further diagnostics. The results of routine CBC and blood chemistry tests at that time disclosed a mild normocytic, hypochromic, nonregenerative anemia (hematocrit, 39% [reference range, 40–50%]; mean corpuscular hemoglo- bin concentration 32 g/dL [reference range, 33–36 g/ dL]), a mature neutrophilia (12,918 cells/mL; reference range, 3,000–10,500 cells/mL), and elevated creatinine (3.2 mg/dL; reference range, 0.5–1.6 mg/dL), SUN (74 mg/dL; reference range, 8–31 mg/dL), and globulin (4.9 g/dL; reference range, 2.3–4.4 g/dL) concentrations. A urinalysis showed a specific gravity of 1.011, 60–80 white blood cells/high power field, and many rods. Urine culture for aerobic bacteria revealed Klebsiella pneumo- niae, which was sensitive to enrofloxacin, tetracycline, and trimethoprim-sulfamethoxazole. An abdominal ultrasound examination disclosed only bilateral renal pelvic mineralization. Treatment with lactated Ringer’s solution e (2.5 mL/kg/h IV) with potassium chloride supplementation e (20 mEq/L), mannitol f (0.5 g/kg over 30 minutes, then 1 mg/kg/h IV), and trimethoprim- sulfamethoxazole g (27 mg/kg PO q12h) was initiated. Five days later, the dog’s creatinine and SUN concen- trations were 1.8 mg/dL and 15 mg/dL, respectively, and From the Departments of Medicine & Epidemiology (Sykes); Pathology, Microbiology and Immunology (Norris, Byrne); Veter- inary Medical Teaching Hospital (Cannon, Affolter); and Employee Health Services (O’Malley), University of California, Davis. Dr. Cannon’s current address is Miami Veterinary Specialists, 8601 Sunset Drive, Miami, FL 33143. Dr. Norris’ current address is 2019 Anderson Rd, Suite C, Davis, CA 95616. Dr. Affolter’s current address is Pfizer La Jolla, 10646 Science Center Dr (CB4), San Diego, CA 92121. Reprint requests: Jane E. Sykes BVSc(Hons) PhD DACVIM, VM: Medicine and Epidemiology, 2108 Tupper Hall, University of California, Davis, CA 95616; e-mail: jesykes@ucdavis.edu. Submitted February 6, 2007; Revised March 23, 2007; Accepted April 27, 2007. Copyright E 2007 by the American College of Veterinary Internal Medicine 0891-6640/07/2105-0033/$3.00/0 Case Reports J Vet Intern Med 2007;21:1108–1112